- 學位論文
表面電漿子波導的有限元素模態分析
Finite Element Modal Analysis of Surface Plasmonic Waveguides
摘要
在本研究中,我們將焦點放在表面電漿電子波導上, 有別於傳統的波導,這種波導具有許多有趣的性質比如其結構遠小於傳統波導,這可使光電路成為一個可能實現的夢. 我們在此採用有限元素法來分析此種波導, 在許多的有限元素法中,我們更採用虛軸波傳播法(ID-BPM)。 根據以往的經驗,這種方法能夠有良好的收斂性,在準確度上也有相當的表現,這些已經被前人驗證過了,所以使用此種方法。在本文中,我們舉出了幾個表面電漿電子的波導來做相關的探討,比如: 金屬凹槽波導 (metal slot waveguide),Λ-楔形物波導 (Λ-wedge waveguide), V-型波導 (V-shape waveguide), 金屬帶線(Metal strip line), and 用表面電漿帶線波導做的方向偶合器 (directional couplers using surface plasmonic strip waveguide). 這些波導結構存在許多有趣的現象比如說: 傳波長度, 場的圖形, 以及其色散關係,等等,對於需要的結構,我們也使用FE-ID-BPM solver畫出能量流(power flow)來做進一步的探討,在此,所有前面提及的結構都將會被詳細的分析討論。
並列摘要
This research is mainly concerned with the study of surface plasmonic waveguide problems using full-vectorial finite element imaginary-distance beam propagation method (FE-ID-BPM). We analyze a waveguide problem using FE-ID-BPM solver with curvilinear hybrid edge/nodal elements to avoid spurious solutions. Moreover, the FE-ID-BPM solver is incorporated into the perfectly matched layer (PML) absorbing boundary condition and can solve the leaky waveguide mode very accurately. Numerical analysis considered in this research include square waveguide, metal slot line, -wedge surface plasmonic waveguide, V-shape surface plasmonic waveguide, metal strip line, strip waveguide, and directional coupler. There exist many interesting features in our studied devices, for example, propagation length for subwavelength surface plasmonic waveguides, the field profiles, the dispersion relation and so on. We also plot the power flow diagrams in the cross-sectional plane for the waveguide structures needed. All the waveguides which we mentioned before are discussed in detail.